UV hood vs Flow Hood
Jeswin
showed me a UV hood. I've never seen that before and I know some
people here talk of laminar flow hoods. So what are some
advantage/disadvantages to the UV hood? First of all, it looks more
compact. I imagine the flow hood needs some vents.
Derek
you from your work (fumes and such as well as biological.) A UV hood
is about protecting your work from you (and other ambient exposures.)
Johnathan Stewart
Class 1 hoods may protect users while doing little for the culture, but Class 2 hoods are used specifically to create a sterile environment to protect the culture.
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kingjacob
Jeswin
> Were these just hoods with UV lights or did they also have flow? I guess it
> could work to keep the workspace sterile while you aren't using it, but I
> always bleach everything before I get started so its a tad redundant. I
> guess It depends what you are working with, but if you are doing synbio
> where you usually dont want mutations, i'd keep the UV away.
>
I asked the guy if it was laminar flow and he said it was UV hood to
prevent cross-contamination for their RNA work. The hood was a large
clear chamber able to fit on a normal lab workbench. They have the
wall mounted flow hoods for other jobs like cell culture.
Nathan McCorkle
UV in this sense is just to break down the RNA, since its more labile
than DNA anyway. I would think it would have small arm holes to
prevent air currents as much as possible, did it?
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Nathan McCorkle
Rochester Institute of Technology
College of Science, Biotechnology/Bioinformatics
Jeswin
> UV in this sense is just to break down the RNA, since its more labile
> than DNA anyway. I would think it would have small arm holes to
> prevent air currents as much as possible, did it?
>
was a bit nervous for the interview to pay close attention to the
equipment. lol
mad_casual
> On Mon, Dec 12, 2011 at 1:59 PM, Jeswin <phillyj...@gmail.com> wrote:
> > On Mon, Dec 12, 2011 at 1:47 PM, kingjacob <kingja...@gmail.com> wrote:
> >> Were these just hoods with UV lights or did they also have flow? I guess it
> >> could work to keep the workspace sterile while you aren't using it, but I
> >> always bleach everything before I get started so its a tad redundant. I
> >> guess It depends what you are working with, but if you are doing synbio
> >> where you usually dont want mutations, i'd keep the UV away.
>
> > I asked the guy if it was laminar flow and he said it was UV hood to
> > prevent cross-contamination for their RNA work. The hood was a large
> > clear chamber able to fit on a normal lab workbench. They have the
> > wall mounted flow hoods for other jobs like cell culture.
>
> UV in this sense is just to break down the RNA, since its more labile
> than DNA anyway. I would think it would have small arm holes to
> prevent air currents as much as possible, did it?
I don't know the exact hood in question, but the UV breaks down
everything, DNA, RNA, Protein, liposomes, acrylics and polycarbonates
(I think) will photo-oxidize and 'craze'.
>
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mad_casual
Some laminar flow hoods will use UV light to sterilize air internally.
Most of the UV hoods I've worked in either; A.) Had a sash switch so
that arms in/out -> lights off/on or B) had a timer that turned the
lights on for X number of hours after use. IIRC, bacterial spores are
about the only thing you need to worry about in a UV hood.
Jeswin
IIRC, bacterial spores are
> about the only thing you need to worry about in a UV hood.
>
Nathan McCorkle
Sent from my mobile Android device, please excuse any typographical errors.
No, he (and I) mean bacterial... it should be easily googlable
Jeswin
> No, he (and I) mean bacterial... it should be easily googlable
>
I assume this is the endospore (from wikipedia articles). The
Firmicutes form these spores but how common are these type of bacteria
in labs? Could they be brought in from outside? That's why I asked if
it was a typo.
CodonAUG
is much better. You will find most hoods are HEPA filtered and have a
UV light to assist with keeping it clean - but UV is still not great.
mad_casual
They're use in lab is fairly typical. The "BT" in "BT corn" is
Bacillus thuringiensis. The entire (or nearly) Bacillus genus is spore-
forming. My familiarity with Bacillus thuringiensis is as a model
organism for Bacillus Anthracis, Bacillus subtilus is used for the
same purpose. I'm no environmental monitoring expert, but I feel
confident in saying that unless you're in a clean room, I would assume
that they're (endospores) there, and probably contaminating anything
that isn't sealed and sterilized.
mad_casual
From one of my alma maters:
https://engineering.purdue.edu/CE/Academics/Groups/Environmental/Details/FacultyInfo/EBlatchley/EBlatchley/Links/InactivationBacillusSpores.pdf
Cathal Garvey
"model" gram positive. In fact, I'm specifically developing a plasmid to
enable easier cloning in this species, because I think it would be far
easier for DIYbioers to use than E.coli. The endospore thing is a
problem if you rely on alcohol alone to sterilise surfaces, but dilute
H2O2 will kill endospores for surface cleaning. Autoclaving and flaming
work perfectly as with any other species.
Although the firmicutes are the only true endospore formers AFAIK, the
Clostridia also make tough spores that can survive boiling or even brief
pressure cycles, and many fungal spores can likewise outlast punishing
conditions. However, even an endospore will succumb to *enough* UV..
it's just that such excessive exposures are costly and pose a
sunburn/cancer risk to anyone directly exposed. So, dilute H2O2 will do.
Easiest cheap source of dilute H2O2 is "Napisan", a brand name form of
sodium percarbonate. Sodium percarbonate is a salt of hydrogen peroxide,
so you don't have to worry about the shelf life of the H2O2, as you can
dissolve it fresh right before use. You do have washing soda (sodium
carbonate) in this mix as well, so you have to wipe surfaces down after
use or deal with a crusty precipitate, but I think that's a fair
tradeoff for the convenience.
All that said, I've been working with B.subtilis for quite a while now,
and I don't find that the lab strain poses much of a contamination
problem. 25min autoclave cycles will sterilise everything very
efficiently, and the lab strains are even susceptible to boiling; they
form very poor quality spores.
All the best,
Cathal
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Simon Quellen Field
Cathal Garvey
testing this plasmid before, but in my hubris I designed it without
antibiotic selection, even for prototyping purposes. It's designed not
to require antibiotics, but in hindsight a cassette would still have
been useful for establishing whether and to what extent everything works!
Thankfully I now have a control plasmid, and I'll shortly have
antibiotics. If direct comparison of transformation methods isn't enough
to test the plasmid by reference to the control, I can PCR in the
resistance cassette from the control to test further.
And the plasmid *will* be biobrick compatible, along with a bunch of
other design goodies. :) Segregational stability should be one!
On 14/12/11 01:50, Simon Quellen Field wrote:
> I'm interested in your progress with gram positive DIY.
>
> Meredith and I both wanted to play with yogurt cultures, but the
> non-availability
> of BioBrick-type plasmids for gram positive bugs made this difficult for
> DIY.
mad_casual
> However, even an endospore will succumb to *enough* UV..
> it's just that such excessive exposures are costly and pose a
> sunburn/cancer risk to anyone directly exposed. So, dilute H2O2 will do.
As I said, my experience with UV was with SPDT-type, sash, or dial
timer switches so that a concerted effort was required to expose
oneself to the UV. The UV was considered more 'last ditch' and 'broad
spectrum' breaking down cells, DNA, RNA, Proteins, toxins, blood
pathogens, etc. If nothing else, it was good for enforcing lab order
and cleanliness, anything that was left out at the end of the night
got a good dose of UV. Kinda like slowly autoclaving all the visible
surfaces in lab every night.